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Everything posted by Turbocharger

  1. Took a couple of weeks away with various lockdown complications... I decided I might do more if it's indoors (and that's half the point of the project anyway). It does *technically* fit indoors on the bump stops, but I snagged a sharp edge on the highest point of the tilt 🙄 Nothing more on the air yet...
  2. Evidently they're not fussed about IVA,v they just want to see some docs or calcs to show it won't all end up in the road when you brake really hard. I'd be inclined to write up your design with any strength/materials calcs, aiming to show that the weakest point is "as good as" what went before. Comparative numbers vs the LR original design should be enough. Consider simple load cases (lateral, longitudinal, vertical), throw in a few section diagrams and work it up to about ten pages, put anything else as appendices.
  3. How "budget"? I've a push-along version with one wheel but it's manually powered and somewhat smaller... 😆
  4. Exactly as you've surmised - it's mail-order fabrication. Email a CAD file, receive your bits. The cycle time will certainly be faster with your own printer (esp depending on where they're printed and posted from!), but there will be more messing about time, certainly to start with. https://www.3dhubs.com/
  5. Some more playing with Disco 2 rear airbags on the front axle yesterday evening - whichever bags I go for, I'm inclined to cant the lower pedestal back a little so that the angle at full droop is less extreme. The minimum length of the springs is going to be very important - I can see why Robert had those extended bump stops - there's 160mm package volume for the spring at full compression to the bump stop, and I'm keen to design it as if the 50mm bump stop was removed, or at least substantially compressed. (Spring cup is upside down to take the air spring piston, as a static mockup) The Disco 2 airbag looks like it'll compress to 140mm, but the bag is overhanging the lower piston - that's not actually an issue once there's any pressure in it because it rolls back like ... (try to avoid a foreskin comparison here). I made a video of it inflating at moderate height - and with the rear pedestal settling and scaring the bejeezus out of me. The Disco2 bag is crimped top and bottom so it appears to have a very long length when it's off the car, but the effective travel when it's inflated isn't much more than the P38 bags.
  6. They'll have done their research, and I'm sure it'll sell. I quite like it 😳 Let me ask - if it wasn't branded 'Defender', would that be ok?
  7. It appears to have a spark plug loose on the intake side of the engine so that's five, just one more to account for...
  8. Looks like we're working on similar projects! Keep in touch, keen to learn by your mistakes rather than my own 😉 Yes, it's possible to make this very complex indeed. Pressure sensors at each corner, 9 axis in the car, maybe a vertical accelerometer on each unsprung mass, add some extra chambers onto each corner which you could activate with their own solenoids... The microcontroller can probably deploy any logic you like - but what's actually desirable? There's a good chance active interventions could be the wrong thing, or the right thing at the wrong time - we know adjustable (passive) shocks etc just gives many more degrees of freedom for any amateur to make it worse. I'm keen to make it self-level, run on the road at a slightly lower height and be liftable for offroad/lowered for the garage. Then to look at how to make it cross axle better with a sensible level of complexity. If I wanted skyhook ride I'd just buy something with a significantly lower unsprung mass. This is never going to be a limousine.
  9. I'd suggest subbing out the fiddling if you're looking for products and not a project. A friend runs a 'farm' of printers and he turns CAD files into objects for other people, then posts them out. His focus is on the production and dimensional accuracy, getting the layers to bind etc, and the risk is his when it chews a reel of filament or spoils a print at 95% progress. His work comes through 3D Hubs, so you can just chuck your CAD file at them. You'll need a fairly large printer for exhaust bits I'd expect, so probably cheaper to rent than buy. Need to be honest with yourself - are you looking for a hobby (the process of printing it) or the output (the finished bits)?
  10. I've done a little more playing at the weekend and got some characteristics for the various springs. The key to getting a decent mix of ride and handling will be to match the natural frequency that the car had on coil springs - this will ensure the shocks are working in something like the envelope they were designed for too. Natural frequency should be between 1 and 2 Hz, and the rear slightly higher than the front (because bumps hit the front end first, usually 🙄). I used a natty free app MyFrequency, which uses the phone's accelerometer data. You can see on the trace when the axle hits bump stops (or a dangling shock absorber 😱), and the low frequency analysis is a little imprecise, but the method is consistent at least. The front suspension came out at 1.6Hz (300Tdi, auto box, Milemarker on the bumper, 6 point cage, red & white RR front springs) The rear suspension came out at 1.7Hz (same powertrain, some tools and old paint tins in the back - this frequency would go up slightly if unladen) The frequency changes slightly at different ride heights - the lower piston is often shaped and there's more air doing the springing if the bag is extended. I've found the RR bags need about 60psi to hold the Ninety up, and the Disco 2 bags nearer to 80psi because they're a smaller diameter. For the front axle, I've found: P38 front airbag 1.9Hz at normal ride height 1.6Hz at +50mm P38 rear airbag - 2.3Hz at -50mm 1.8Hz at normal ride height 1.9Hz at +50mm Disco 2 springs - (still to fit) For the rear axle, I've found: P38 front airbag 1.7Hz at -50mm 1.6Hz at normal ride height 2.0Hz at +50mm P38 rear airbag - (still to fit) Disco 2 rear airbag 1.9Hz at -50mm 1.6Hz at normal ride height 1.8Hz at +50mm 1.9Hz at +120mm So if all these measurements are +/- 0.3Hz, it looks like we're in the right ballpark with any of these springs so I'll select based on what I can package and what will give a balanced setup. The Disco 2 bag is seriously long - they're a crimped design so harder to play with pistons, change bags etc, but... Thanks to Andy for some prior experience - this really is the most useful way to learn anything! Thanks Andy - really good to see the experience of someone who's been through the pain before. Looking at the frequency stats I'd say this was quite a soft ride (depending on the shocks you used) but the background suggests this was an offroad truck so that's probably ok? The lower piston isn't shaped so those force charts (top right graph) are nice and flat in the middle area. I'm keen to avoid the kind of extended bump stops you've used so packaging a short compressed length between the upper spring chair and the axle mount will be a challenge, and then getting the most travel available from the bag and any matching shock absorber.
  11. Yes, and swapping the pistons and top pieces is an interesting route to tweak the characteristics a little. Disco 2 bags are crimped on though. They're not magic - it's a spring so doesn't provide skyhooks. They help to separate out the spring rate from the ride height though, so you could run a soft spring without one end being droopy when laden. The car on top of the spring/shock makes a huge difference, clearly. A lot of 'feeling every bump' is down to the damping though, and it's very hard to get any numbers on damping characteristics or rates. The best I've found is Gwyn Lewis who's characterised four different shocks, no numbers but 'by feel' is sensible. (I've got Fox 2.0 IFPs on the front of mine and very very pleased with their high speed damping particularly, but they replaced some knackered ProComps so hard to get a proper back to back. Gwyn says: (from eg here:https://gwynlewis4x4.co.uk/product/challenge-old-man-emu-5-5-inch-shocks-four/)
  12. Yes - I think they've made a new upper housing complete - I expect I'll end up making something like this (but probably not as pretty). At present I'm fitting springs with bits of wood etc to better understand which springs will suit a softtop Ninety best - and to understand why.
  13. No 🙄 I think they're too small - 1/8NPT would be 9.5mm OD across the male thread and ~0.9mm pitch, these are 7.7mm OD and 0.75mm pitch.
  14. The P38 compressor runs through a 30A fuse (so it's less than 400W then). I've just bench tested mine from a battery and saw 2.5A (30W) but that's not running against any pressure, just motoring the piston up and down. Thanks for the chassis info - it explains the strange shape of the P38 rear top cups, but I've got enough info to work up what I need. Like I said, modifying a new galv chassis isn't on the menu so it'll go back to coils if I can't make what I have fit.
  15. Paddock do (well, did - no online shop 😷) the relocation kit I got to put the shock in that forward position, it's galv but not the highest quality. It'll do for now.
  16. LSE and standard RRC have the same spring part number, I believe. The difference would probably have been made up by a slightly higher pressure by the time the levelling process had done its work. Great P38 pics Ed, thanks. At the moment I've wedged some bits of wood in the gaps to trial-fit the springs while I assess the frequencies. They're wrong, but not so wrong they wouldn't work with an adaptor piece top and bottom. Disco 2 rear airbags are still an option for one/both ends - different fittings turned up and (bad news) they're not standard M8 but (good news) not so far away so they'll screw in far enough for an O-ring to seal before it all goes horribly tight. The fitting it really needs (top of pic below) is 7.7mm OD across the male threads and 0.75mm pitch or some dark hex fraction of an inch equiv. Could be M8 fine pitch? (The bottom one is today's M8 Amazon delivery).
  17. P38 bottom and certainly the top housing isn't compatible with a Defender chassis. I've got some RRC airbags on the way when I can collect (post-Corona) for more checking. I *believe* the actual rubber bladder is the same diameter but a P38 (especially the rear) is longer. I may yet try 3D-printing some top and bottom housings to take the longer P38 bags - that would provide an opportunity to shape the piston for spring rates at different heights, and add extra volume above the spring chair for a lower rate (or a large bore for a fitting for an additional switchable volume). For now, let's see if the spring frequencies are even slightly close to coils and assess how it drives on P38 bags.
  18. I think Arduino would suffice. There's an argument for doing this with discrete components, with some non-PWM solenoids it's just an OpAmp and some relays really. It's chilly but sofa research has yielded some plug wiring diagrams, thanks to http://paulp38a.com/range-rover-p38/how-eas-works/ for example:
  19. I'll have a look at this. Arduino still has a leg up because I already own one, but it looks like I'll run out of IOs if I want a display and any accelerometer or GPS (for road speed) input, so I'll look at alternative hardware then.
  20. 1/4BSP would be 13.1mm OD though, this is 7.8mm ish. An M8 bolt screws in "a bit", same for a nut onto the fitting, which says it's something pipe-thready? https://www.thehosemaster.co.uk/bsp-pipe-threads
  21. The OE LandRover fitting is definitely 7.7ish OD. Question is why the 1/16BSP fitting I ordered has turned up and is 4.4mm?
  22. Now, what have I done wrong? Td5 Disco airbag has a screw fitting in the top, 7.7mm OD across the threads which corresponds to 1/16BSP. I ordered a push fit connector (from China 😷) but it's turned up far too small, at 4.4mm OD. Looking at the eBay picture, that's what they were selling (scaling from the 6mm push-fit pipe), so is the mistake theirs or mine?
  23. Convince me further. I like the wide community support available for the Arduino - I think it'll do what I want and I can appeal to the cleverer people when it doesn't work properly... 😁
  24. There's several plugs. For each I got the corresponding length off the P38 but that's a limited supply and the wires are old and brittle. Compressorhas a chunky plug with (I presume) power, ground and something from the pressure sensor to trigger it. The solenoid box has two plugs (red & purple) and presumably the slave ECU (yellow) which does the PWM magic. I'll be replacing this with MOSFETs controlled by the Arduino. The purple plug is internal to the box and presumably runs one of the solenoids or a sensor. The red plug would be handy to interface with: Looks like I was smart enough to get the corresponding bits off the P38 too so should be ok with these until I break either. The height sensors each have a short tail of old brittle loom so these will be more of a problem in the longer term. Any ideas for these?
  25. I'm hoping by controlling airflow between the two outer bags that it'll achieve the same aim - a kind of 'virtual' central bag. Only experience will tell if that works though. Bits turned up for the Disco 2 bags today, so that's the next session covered for fact seeking and investigation. I'm going to need electrical plugs to match the height sensors and ideally the P38 solenoid block box too - any ideas where to source these (at sensible money)? Otherwise I'll just cut them off, extend the wires and find something suitably waterproof which I can populate the pins myself.
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